This invention relates to computer systems and more particularly to an apparatus for handling and storing optical disk cartridges. Even more particularly this invention relates to detecting the position of moving mechanisms within the control system of such apparatus.
An optical disk is a data storage medium which is readable by a laser-based reading device. Optical disks known as "compact disks" or "CDs" have become increasingly popular during the past few years for recording music and audio-visual works. Due to the huge storage capacity of optical disks as compared to conventional magnetic storage media, optical disks known as "ROM disks" have become popular for storing computer readable information. Recent technology has produced optical disks which can be written as well as read by the computer, thus, in the future optical disks are expected to become increasingly more important in the computer industry and may eventually replace magnetically readable and writable storage media such as "floppy disks" and "hard disks." Another recent development, the ability to provide data storage on both surfaces of an optical disk, has effectively doubled the optical disk storage capacity.
Optical disks of the type used in computer applications are generally mounted in cartridges, and the reading devices generally read or write data through a slot provided on a surface of the cartridge. Currently, most optical disks are hand-inserted into disk readers. However, for large databases consisting of many optical disks, it is preferable, and perhaps essential, to provide an optical disk storage system for storing the disks at known locations, and an optical disk handling system which is capable of retrieving a desired disk from a storage location and inserting the disk into an optical disk reader. In a disk storage system wherein the stored disks and an associated disk reader are arranged in a longitudinally extending, two-dimensional array consisting of vertically extending columns and laterally extending rows, it is necessary for a disk handling system to be capable of engaging a disk, moving it vertically, laterally, and longitudinally and then releasing it in order to remove it from storage, move it into aligned relationship with the disk reader, and insert it into the disk reader. It may further be necessary for the disk handling system to flip the disk to reverse the side thereof which will be positioned in readable relationship with a reader. It may also be necessary to reorient a disk at the time it is initially inserted into the system by an operator.
In order to decrease production and maintenance costs and to increase reliability of such a disk handling system, it is generally desirable to reduce the number of separate control systems to a minimum. It is also desirable to minimize the use of sensing devices which are particularly subject to malfunction such as, for example, photoelectric or magnetic proximity sensors. It is also desirable to minimize the mounting of sensors or motors on moving system components to eliminate problems associated with moving lead wires, etc.
There is need in the art then for a system that detects the location of its mechanisms using a minimum number of sensors. There is a further need for such a system that performs such detection using sensors that are not mounted on moving mechanisms. A still further need is for a system that detects obstructions without a separate sensor for such detection. Another need is for a system that will detect the presence of a cartridge without a separate sensor for such detection. Still another need is for a system to detect the location of its mechanisms by monitoring the force being exerted by such mechanism.
Various features and components of such a cartridge handling system are disclosed in U.S. patent applications:
(A) Ser. No. 278,102 filed 11/30/88 for OPTICAL DISK PA1 HANDLING APPARATUS WITH FLIP LATCH of Methlie, Oliver, Stavely and Wanger; PA1 (B) Ser. No. 288,608 filed 12/22/88 for OPTICAL DISK INSERTION APPARATUS of Christie, Wanger, Dauner, Jones and Domel; PA1 (C) Ser. No. 289,388 filed 1/18/89 for LATERAL DISPLACEMENT CONTROL ASSEMBLY FOR AN OPTICAL DISK HANDLING SYSTEM of Wanger, Methlie, Stavely and Oliver; and PA1 (D) Ser. No. 305,898 filed 2/2/89 for OPTICAL DISK CARTRIDGE HANDLING APPARATUS WITH PASSIVE CARTRIDGE ENGAGEMENT ASSEMBLY of Wanger, Methlie, Jones and Stavely; PA1 (E) Ser. No. 314,012 filed 2/22/89 for CARTRIDGE HANDLING SYSTEM of Wanger, Methlie, Christie, Dauner, Jones, Oliver, and Stavely,
which are each hereby specifically incorporated by reference for all that is disclosed therein.